Manufacture of hypophosphoric acid and of its salts.



' lmitspreferably from 3 to 10 volts a good yield of hypophosphoric acid-up to 60% of the phosphorus entering into solution is obthe quantity of phosphorus and hypophosanode is dissolved. Then the electrolyte is UNI ED STATES PATENT canton;

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MANUFACTURE or :axrornosrnomc non) AND. or ITS saws.

ture of hypophosphoric acid'and of its salts and consists in electrolytically oxidizing anodes consisting of phosphids. Suitable phosphids are forinstance phosphids of copper, silver, nickel and tin. The electrolysis is preferably effected with a weak acid electrolytical bathand with a cathode consisting of the metal contained in the phosphid. If the voltage is kept in suitable tained in addition tophosphoric acid. If the voltage is permanently kept higher the percentage of phosphoric acid is increased if on the contrary the voltage is kept lower phorous acid increases.

Care is to be taken that in acidulating the bath solution strongly oxidizing acids such as nitric acid or acids which develop oxidizi products during electrolysis such as h ifiogenous hydrogen'acids and acids of low conductive property are avoided. Sulfuric acid as a solution of 1 to 10% and formic acid of the same concentration are most available. Small quantities of compara tively weak oxidizingagents such as chromic acid may be added to the electrolyte as catalytic substances.-

The electrolysis can beeffectedwith' or without diaphragm for separating the anode space from the cathode space;

. The electrolysis is kept in operation till the most part of the metal phosphid used as drawn off or separated from the metal 5 on e by filtering. The electrolyte may ti enfiie used directly as a solution of hypophosphoric acid or half of its volume may be Specification of Letters Patent. Application filed June 21,1911. Serial No. (534,408.

Patented Oct. 29,1912.

-' addition to the second half of the electrolyte the liquid may be concentrated .so that the diiiicultly soluble acid sodium hypophosphate NaHPO 2H O, is crystallized. out from the solution.

What I claim is: g

1'. Process of manufacturing hypophostrolytically oxidizing inetalphosphid anodes.

2. Process of manufacturing hypophosphoric acids and its salts comprising elec- 1 trolytically oxidizing metalphosphid anodes metal of the phosphid anodes.

3. Process of manufacturing hypophosphoric acids and its salts comprising elec from 3 to 10 volts.

phoric acids and its salts comprising electrolytically oxidizing metalphosphid anodes in a weakly acid electrolyte at a voltage from 3 to 10 volts in opposition to cathodes 5. Process of manufacturing hypophostrolytically oxidizing metalphosphid anodes substantially free from acids, with strongly 7. Process of manufacturing hypophosphoric acids and its salts comprising elecin a'weakly acid electrolyte containing small quantities of weakly'oxidizing substances.

In testimony in presence of twowitnessesl ARTH R ROSENHEIMJ \Vitnesses: I

HENRY HASPER,'

neutralized by carbonate of soda and after Copies 0! this patent may be obtained for five cents Washingt 'WOLDEMAR HAUPT. w

each, by addressing the Commissioner of Patents, on, D. G.

phoric acids and its salts comprising electrolytically oxidizing metalphosphid anodes, inv a weakly acid electrolyte at a voltage- 4. Process of manufacturing hypophoscontaining the metal of the phosphid anodes.

containing the metal of the phosphid anodes.

trolyticall oxidizing \metalphosphid anodes whereof, I aiiix my signature in opposition to cathodes containing the phoric acids and its salts comprlsing elecin a well conducting weakly acid electrolyte 

